Toroidal Inductors

TOROIDAL INDUCTORS

Application Notes > Custom Inductors > Toroidal Inductors
Gowanda designs and manufactures Custom Toroidal Inductors for a variety of power supply and power conversion applications. A Toroidal inductor is an inductor that is designed on a doughnut shaped core. Toroidal inductors offer small size, less leakage inductance and lower electromagnetic interference (EMI).

Toroidal Inductor Applications

  • Switch mode power supplies
  • Filter applications
  • Electromagnetic Interference (EMI) sensitive circuits

Toroidal Inductor Design

  • Typical minimum requirements to be specified for a Toroidal inductor design are:
      • No load inductance in µH
      • Full load inductance in µH
      • DC Current in Amps
      • AC Current in Amps peak to peak
      • Operating frequency is needed for core calculations and wire sizing
  • Core material is selected for the known operating frequency or frequencies.
  • Other Toroidal inductor design considerations are space limitations and mounting technique.
  • Lead terminations are also specified through the design of a Toroidal inductor.

A Toroidal Inductor design may vary widely in terms of power rating, inductance, voltage level (low to high), operating frequency, size, impedance, bandwidth (frequency response), packaging, winding capacitance, and other parameters.

Photo Gallery

This image is of a toroidal inductor with 2 leads showing. The tape secures the leads to the coil so that the leads do not move. The 3 toroidal cores have been secured together and have been wound with magnet wire. The completed assembly is dipped in air dry varnish and then used in a medical application.

Here we see a bin of toroidal inductors that have been wound and have leads attached to the winding. These leads will make the electrical circuit connection.

The same inductors as in the previous image are now placed in a potting cup and are ready for encapsulation, when the cup is filled with epoxy.

Dual Wound Toroidal Inductors

Series L µH DCR Ohms Current Rating mA DC
SMT35A 0.22 – 300 0.0028 – 1.0060 0.29 – 5.47
SMT45A 0.22 – 300 0.0026 – 0.6750 0.37 – 6.09

Low Current Toroidal Inductor

SeriesL
µH
DCR
Ohms
Current Rating
mA DC
 
LCSM1.1 – 19500.011 – 1.700.60 – 5.40

Radial Lead Toroidal Inductor

Series L µH DCR Ohms Current Rating mA DC
AT 10 – 1000 0.010 – 0.240 1.69 – 30
ATHC
ATHM
ATRM
ATVC
GT10
GT20
HF
HT
KM
KMHC
KMHM
KMRM
KMVC
PX

Shielded Toroidal Inductor

SeriesL
µH
DCR
Ohms
Current Rating
mA DC
 
SMT31061 – 10000.016 – 8.230.18 – 4
SMT40151 – 3300.0030 – 0.520.88 – 11.6

Vertical Toroidal Inductor

SeriesL
µH
DCR
Ohms
Current Rating
mA DC
 
SMP20070.15 – 150.006 – 0.0601.9 – 5.9